1. Field of the Invention
The present invention concerns a socket contact for electrical connectors the socket contact having a box shaped sheet-metal frame and four contact elements incorporated therein as well as a connection part for cables, which adjoins the sheet-metal frame, and in which the sheet-metal frame has a front frame part and a rear frame part. Such a socket contact is known, for example from EP-A-255 245.
Socket contacts are used in particular in signal transmission for control devices with a high number of poles, such as for example motor control devices. Since a large number of connector pins are provided in a plug-in connector, a compact design of these connector sockets is very important. The reinforcing cages of the connector sockets typically have transverse dimensions of 2xc3x972 mm.
Since a plugging operation involves inserting a large number of connectors into corresponding sockets, the inserting force to be expended must mot be too great and at the same time satisfactory electrical contact and adequately high retaining forces must be ensured.
2. Description of the Prior Art
EP-225 245 A1 describes a socket contact of the type specified in the precharacterizing clause of claim 1. In this case, the insertion region is designed as a box-shaped sheet-metal frame with four contact tongues, which are fastened on both sides to frame parts and have contact points formed in the vicinity of the insertion region. The contact points are staggered by pairs by a short distance and the tongues are all of the same design, with the result that the entire spring force of all four resilient tongues acts within a short time interval during the insertion operation, with the result that, if up to 50 connector pins of a plug-in connector are inserted simultaneously into a corresponding connector socket, the insertion force is very high during that short time interval.
EP-353 330 describes a socket contact for electrical connectors in which contact elements comprise resilient elements, with a free head end, the contact elements being arranged lying one behind the other in the direction of insertion. In this way, the insertion force is distributed over time and is consequently spread evenly throughout the insertion operation. The mutually opposite points of the resilient elements are not the same. The free end of a long resilient tongue and a contact element bent inwards from a short cutout respectively lie opposite one another. A relatively rigid guidance of the connector to be inserted consequently takes place at these relatively inflexible protrusions, with the result that a jammed insertion is of the connector pins is avoided. Furthermore, the spring deflection of the resilient tongues is limited by little space being provided for free movement within the reinforcing cage.
EP-A-727 843 discloses an asymmetric electrical receptacle terminal having a box-shaped sheet-frame and contact arms separated from the frame by a certain gap to allow outward biasing thereof.
The present invention is based on the object of improving a socket contact of the type mentioned at the beginning in such a way that optimum electrical contacting and high retaining forces are realized with low insertion forces distributed throughout the entire insertion operation.
This object is achieved as claimed. Preferred embodiments of the invention are characterized in the subclaims.
According to the invention, at the insertion end of the box-shaped socket Connector, the xe2x80x9cboxxe2x80x9d is in two parts, with respectively two sides joined together via an edge forming a unit. That is to say, resilient elements whose spring deflections form an angle of 90xc2x0 with respect to one another are fastened on one part of the xe2x80x9cframexe2x80x9d and the same arrangement is to be found diametrically opposite. Consequently, the flexibility of the contact elements is not limited only to their own spring deflection, but instead the box frame can partially covibrate in the reinforcing cage. As a result an insertion force is accomplished, which is distributed more evenly throughout the insertion operation than in the case of the prior art.
The invention is explained in more detail below on the basis of the description of an exemplary embodiment with reference to the drawings, in which:
FIGS. 1a and b show two perspective views of the socket contact according to the invention with the reinforcing cage pulled off, and
FIG. 2 shows three perspective views of the socket contact according to the invention with the reinforcing cage fitted.